作　　者： (宋超）; (王攀）; (韩贵琳）; (石迎春）;

机构地区： 中国地质科学院水文地质环境地质研究所,石家庄050061 中国地质大学（北京）水资源与环境学院,北京100083

出　　处： 《南水北调与水利科技》 2017年第5期121-126,共6页

摘　　要： 对甘肃省灵台县独店镇秋射村黄土剖面浅层地下水的水化学组成、溶解无机碳(DIC)、溶解有机碳(DOC)、颗粒有机碳(POC)等进行了取样分析,对其δ^(13)CDIC和δ^(13)CPOC的特征及其控制因素进行了探讨,并评估了降雨补给过程中的碳酸盐风化碳汇强度。结果表明,研究区地下水的水化学类型为HCO3-Ca·Mg型,其方解石饱和指数SIC大于0,已经饱和,但尚未达到大规模沉淀的程度。研究区黄土浅层地下水的DIC变化范围为5.25~5.45mmol/L,DOC含量为0.59~0.62mg/L,明显低于地表水体;而POC稍高,这是因为黄土颗粒物的混入造成。泉水和井水的δ^(13)CDIC变化范围在-9.19‰^-8.90‰之间,其较高的δ^(13)C与碳酸盐风化-沉积过程中反复的碳同位素交换有关。而δ^(13)CPOC变化范围在-19.99‰^-18.87‰之间,与黄土有机碳同位素特征基本一致。地下水中的HCO-3、Ca2+和Mg2+主要来源于碳酸盐的化学风化。根据风化反应的离子平衡关系,计算得到研究区的风化碳汇为2.82mmol/L,即每有1L的降水入渗到零通量面以下,就会产生2.82mmol的碳汇。 We analyzed the hydro-chemical composition,dissolved inorganic carbon（DIC）,dissolved organic carbon（DOC）,particulate organic carbon（POC）in the shallow groundwater of a loess profile in Qiushe village,Dudian town,Lingtai county,Gansu province of Northwestern China,discussed the characteristics and controlling factors of the δ^（13）CDIC and δ^（13）CPOC,and assessed the CO_2 consumption of carbonate weathering during rainfall recharge.The results showed that the hydro-chemical type of the groundwater in the study area was the HCO3-Ca·Mg type.The saturation index of calcite（SIc）was above 0,indicating full saturation but no massive precipitation yet.The DIC concentration in the shallow groundwater of the loess area was 5.25~5.45mmol/L and the DOC concentration was 0.59~0.62mg/L,which were lower than those in surface water.The POC concentration was high due to the mixture of loess particle matter.The δ^（13）C of DIC in spring water and well water ranged from-9.19‰to-8.90‰.This might be associated with the repeated exchange of C isotope during the process of carbonate weathering and precipitation.The δ^（13）CPO Cranged from-19.99‰ to-18.87‰,which was consistent with the isotope ratio of the organic carbon in loess.The HCO-3,Ca^（2＋） and Mg^（2＋）in groundwater mainly came from the weathering of carbonate in loess.According to the ion balance of carbonate weathering reaction,we calculated the CO_2 sink by carbonate weathering in the study area to be 2.82 mmol/L.In other words,2.82 mmol CO_2 can be absorbed by carbonate weathering when every 1 Lrainfall infiltrates below the zero flux plane.

关 键 词： 黄土 地下水 泉水 水化学 无机碳 碳循环